Calculating wavelengths of light

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  • Thread starter Thread starter YamunaVargr
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    Light Wavelengths
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SUMMARY

The discussion centers on calculating the wavelength of light necessary to excite the pi electrons of B-carotene from the n=11 to n=13 energy levels. The participant mentions that the wavelength of light for B-carotene is typically around 450 nm, which is associated with its orange color. However, they express confusion regarding the calculations needed to determine the correct wavelength, specifically referencing the particle in a box method and the role of pi electrons and conjugation length. The participant seeks clarification on the mathematical approach required to accurately determine the wavelength.

PREREQUISITES
  • Understanding of quantum mechanics, specifically energy levels in molecular orbitals
  • Familiarity with the particle in a box model in quantum physics
  • Knowledge of pi electron systems and conjugation in organic molecules
  • Basic principles of photon energy and wavelength calculations
NEXT STEPS
  • Study the particle in a box model in greater detail to understand its application in calculating energy levels
  • Learn about the relationship between energy, wavelength, and frequency of photons
  • Research the concept of conjugation and its effect on the electronic properties of molecules
  • Explore the calculation of energy transitions in molecular orbitals using the formula E = hc/λ
USEFUL FOR

Chemistry students, particularly those studying organic chemistry and quantum mechanics, as well as educators and researchers interested in the electronic properties of molecules like B-carotene.

YamunaVargr
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So. I need to calculate the wavelength of light that's required in order to excite the pi electrons of B-carotene from n=11 to n=13. The Length of the wavelength of L is 17.7 A.
I know how to look at the particle in a box method. And I know that the wavelength of light for B-carotene is 450, which is why a carrot is orange.
But I'm not quite grasping how to get the answer. 450 was incorrect.
Is there some math that I'm not realizing that I need to do?
I feel it should have something to do with the amount of pi electrons? Or the length of the conjugation chain?

Any input would be really helpful. This my first class on this subject, and I'm trying to stay caught up with all the new information.
 
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If a photon comes from outside, or if the molecule is irradiated with light, electrons in the HOMO can be excited to the Lumo.
(I think that's what I'm going for.)
The energy difference between the two molecular orbitals or two states should correspond to the energy of the photon whose wavelength is 450 nm.

I feel like there should be a relatively simple way of going about this.
 

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